Mysteries of Thunderstorms

Reported October 2006

HUNTSVILLE, Ala. (Ivanhoe Broadcast News) -- There's no mistaking the billowing clouds, the noise, the rain, and the lightning of a thunderstorm. But why do some dark and ominous clouds form into huge masses of rain and lightning while others just pass us by?

We'll likely see a big storm roll-in on warm days, but you might be surprised to learn thunderstorms are also filled with ice!

"Ice plays a big role in the amount of rain that you see." Walter Petersen, Ph.D., an atmospheric scientist at University of Alabama, Huntsville, tells Ivanhoe.

He says ice in clouds is the key to really big electrical storms. Ice creates lightning and often heavy rain.

"A fair amount of rain that you see over continents actually is the result of melting ice that's created high up in the, high up in the development of thunderstorms," Dr. Petersen says.

Ice is vital to the development of lightning. Different-sized ice particles within a cloud carry a positive or negative charge. As the particles collide, that charge builds up. When the charge is released -- we see lightning.

Satellites watch lightning flashes from space, helping scientists to learn more about them.

"We know how much ice is associated with a given number of lightning flashes," Dr. Petersen says. "Then we can say something about the amount of rain that falls out of those clouds." Knowing the rain that falls was once ice above you -- a heads up about what's really inside a thunderstorm.

Click here to Go Inside This Science or contact:

Walter Petersen, Ph.D.
Meteorologist
University of Alabama-Huntsville
Huntsville, Alabama
(256) 961-7861

The American Meteorological Society
Boston, MA 02108-3693
(617) 227-2425
http://www.ametsoc.org

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